Blade-securing means.



F. HODGKINSON. BLADE SEQURING MEANS. APPLIGATION FILED APR. 10, 1911 Patented Dec. 3, 1912.

WITNESSES:

IN VENTOR.

HIS ATTORNEY IN FACT.

snares PATET FRANCIS HODGKINSON, F EDGEWOOD PARK, IPENNSYLVANIA, ASSIGNOR TO THE WESTINGHOUSE MACHINE COMPANY, A CORPORATION OF PENNSYLVANIA.

B'LAnE-sEcURInG MEANS.

Specification of Letters'Patent,

Patented Dec. 3, 1912.

To'all whom it may concern:

Be it known that I, FRANCIS HODGKINSON,

' a subject of the King of Great Britain and Ireland, and a resident of Edgewood Park, in the county of Allegheny and State of Pennsylvania, have made a-new and useful Invention .in Blade-Securing Means, of

. which the following is a specification.

. in connection with turbines of the Parsons type,the centrifugal force upon the blades is liable to cause them to become loose, and, manifestly, a loose blade in a turbine is a very serious menace to the rest of the blades.

It is one of the. objects of my invention to provide a blade-securing means, which will eificiently hold the blades in place and prevent their'becoming loose in the actual I operation of the turbine.

In carrying out my invention, I preferably construct the blade of a strip of metal drawn to blade shape and provide a-lip or foot-at the bottom thereof which may be formed by a die and bulldozer by upsetting the end of the blade. The upset root or foot of the blade is considerably stronger than a bent-over portion would be, for, manifestly, the upsetting'of the blade root forces the molecules of the metal closer together,

' and if desired the roots may be made of anythickness. The blade root is preferably of less width than the width of the blade, so that it may fit into a groove in the wall of the ordinary turbine blade receiving groove. The'thickness of the 'root is preferably that of the height of the wall of the supplemental groove, so that the packing pieces may rest firmly upon the floor of .the turbine groove and over the root of the blade so that these packing pieces need not be weakened or cut to receive the root. The packing pieces are preferably inserted in undercut groovesa-nd' wedged in place so that they need not necessarily be calked in the grooves,-bu t may be held in place by wedges so that in the event that some of the blades need notbe taken out for repairs,

or for other purposes, the wedges, packing pieces and blades may be removed with case.

In the drawings forming a part of this specification, Figure 1 is a fragmentary perspective view of a blade-holding element in which blades constructed in accordance with my invention are shown. Fig. 2 is a plan view of a portion of a blade-holding element showing the blades in place. Fig. 3 is a longitudinal sectional view on the line 3-3 of F ig. 2. Fig. -:l is a perspective view of a blade showing the relation of the packing piece in dotted lines. Fig. 5 is a cross-sectional view of a blade-holding element in which a blade and packing piece are secured, and Fig. 6 is a view of a slight modification.

Referring now to Fig. 1: 10 designates a blade-holding element provided with a groove 11in which is a sub-jacent or supplemental groove 12 in the floor thereof. The sides of the groove 11 are preferably inclined as at 1 3 and 1 1 to provide under-cut portions for the respective packing pieces and wedges.

The blade is best illustrated in Fig. 4 and is shown as comprising a blade portion 15, having a foot or root-16 at one end thereof, which foot may be formed by being die-struck in a bulldozer so as to upset the metal. In actual practice, the upsetting of the end of the blade may extend elntirely across the blade, but portions of the root or foot may be cut away so that said foot will be narrower than the width of the blade. In actual practice it is desirable that this foot shall be of approximately the width of the groove 12 and of approximately the same thickness.

The manner of inserting the blades is best shown in Fig. 1 in which the blades are inserted in the groove 11 so that at least one over-lapping portion 17 will rest upon the floor of the groove 11, and the foot or tongue will be within the groove 12. If desired, the thickness of. the root may be 12 so that a space 18 is provided between the bottom of the root and the floor of the groove 12 to allow for contraction and expansion of the root in actual practice. After the bladeis put in place, a packing piece 19 is inserted which is of greater width than the width of the blade and which has an inclined portion 20 fitting slightly less than the depth of the groove approximately the same plane as the floor meet at the roots.

within the undercut portion of the groove 11, formed by the side-wall 13. The opposite side of the packing piece l9'is preferably straight, as indicated at 21.

From an inspection of the drawings, Figs. 1, 2 and 5, it will be observed that a space is .formed between the ends of the packing pieces, the blades and the side wall 11 of the groove 11. This space may be filled by compound tapered wedges designated as 22 and 23, which force the packing pieces to engage-the undercut side of the groove 11 and hold the blades in their proper operative position. It will be observed that the tops of the roots of the blades are in of the groove 11, so that the packing pieces may fit snugly over them and hold them in place. The packing pieces need not be calked so as to contractthem in engaging the undercut surface of the groove, but ander certain conditions, it might be necessary to provide a slight calking to tighten up the relationship 'of' the packing pieces and their wedges. In n'p case, however, will the calking extend to'causing the packing pieces to flow into the undercut portions of the groove 11. If the blades and packing pieces are held in place by wedges the last of the packing pieces and blades may be put in in a manner common to the practice now generally employed. Under certain conditions the wedges need not be employed, but the supplemental groove will be used with the blade having a foot or root of less width than the body portion of the blade. I may also employ a blade of inverted T-shape if desired, as shown at 15",

Fi 6. Y

l rem theforegoing, it'will be apparent that the blades'will be held readily in place and that any liability of them becoming loose or separated from their roots will be avoided, inasmuch as the'blades are strong- In actual practice it has been found that blades secured in place in accordance with the structure and manner heretofore set, forth, have actually withstood a pulling strain to the extent that the blades have'been drawn or pulled apart in their body portions, while the roots have re mained intact with the blade-holding ele-- ment. Therefore, it will,.,be seen that the blade and its securin means are both simple and efficient for the purpose intended.

In accordance with the provisions of the patent statutes, I have describedth'e principle of operation of my invention, together with the device which I now consider to.

Holding element having a subjacent groove in the floor of the first named groove, a blade having a foot or projection at one endthereof, the foot being of approximately the same widthas the width of the subjacent groove, and the blade being of greater width than the width of the subjacent,

groove, but less width than the width of the first named groove, a packing piece for holding the blade in place and engaging an undercut portion of the groove, and wedges for holding thepacking pieces in place.

2. The combination with a grooved bladeholding element having a groove; in the floor of the first named gr0ove,'a blade having a projection at right-angles to its body portion and resting in the second mentioned groove, packing pieces in the finst mentioned groove for holding the foot of the blades in place, and wedges for holding the packing pieces in their groove.

. In testimony whereof, I have hereunto subscribed my name this 7th day of April, 1911. I

FRANCIS HODGKINSON. Witnesses: p

C. W. McGrmn,

JO N A. ELDEN. 

